//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <unordered_map>

// template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
//           class Alloc = allocator<pair<const Key, T>>>
// class unordered_multimap

// void swap(unordered_multimap& __u);

#include <unordered_map>
#include <string>
#include <set>
#include <cassert>
#include <cstddef>
#include <iterator>

#include "test_macros.h"
#include "../../test_compare.h"
#include "../../test_hash.h"
#include "test_allocator.h"

#include "min_allocator.h"

int main(int, char**) {
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef test_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    C c1(0, Hash(1), Compare(1), Alloc(1, 1));
    C c2(0, Hash(2), Compare(2), Alloc(1, 2));
    c2.max_load_factor(2);
    c1.swap(c2);

    LIBCPP_ASSERT(c1.bucket_count() == 0);
    assert(c1.size() == 0);
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator().get_id() == 1);
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    LIBCPP_ASSERT(c2.bucket_count() == 0);
    assert(c2.size() == 0);
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator().get_id() == 2);
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef test_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a2[] = {
        P(10, "ten"),
        P(20, "twenty"),
        P(30, "thirty"),
        P(40, "forty"),
        P(50, "fifty"),
        P(60, "sixty"),
        P(70, "seventy"),
        P(80, "eighty"),
    };
    C c1(0, Hash(1), Compare(1), Alloc(1, 1));
    C c2(std::begin(a2), std::end(a2), 0, Hash(2), Compare(2), Alloc(1, 2));
    c2.max_load_factor(2);
    c1.swap(c2);

    assert(c1.bucket_count() >= 8);
    assert(c1.size() == 8);
    assert(c1.find(10)->second == "ten");
    assert(c1.find(20)->second == "twenty");
    assert(c1.find(30)->second == "thirty");
    assert(c1.find(40)->second == "forty");
    assert(c1.find(50)->second == "fifty");
    assert(c1.find(60)->second == "sixty");
    assert(c1.find(70)->second == "seventy");
    assert(c1.find(80)->second == "eighty");
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator().get_id() == 1);
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    LIBCPP_ASSERT(c2.bucket_count() == 0);
    assert(c2.size() == 0);
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator().get_id() == 2);
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef test_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a1[] = {
        P(1, "one"),
        P(2, "two"),
        P(3, "three"),
        P(4, "four"),
        P(1, "four"),
        P(2, "four"),
    };
    C c1(std::begin(a1), std::end(a1), 0, Hash(1), Compare(1), Alloc(1, 1));
    C c2(0, Hash(2), Compare(2), Alloc(1, 2));
    c2.max_load_factor(2);
    c1.swap(c2);

    LIBCPP_ASSERT(c1.bucket_count() == 0);
    assert(c1.size() == 0);
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator().get_id() == 1);
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    assert(c2.bucket_count() >= 6);
    assert(c2.size() == 6);
    {
      std::set<std::string> s;
      s.insert("one");
      s.insert("four");
      assert(s.find(c2.find(1)->second) != s.end());
      s.erase(s.find(c2.find(1)->second));
      assert(s.find(std::next(c2.find(1))->second) != s.end());
    }
    {
      std::set<std::string> s;
      s.insert("two");
      s.insert("four");
      assert(s.find(c2.find(2)->second) != s.end());
      s.erase(s.find(c2.find(2)->second));
      assert(s.find(std::next(c2.find(2))->second) != s.end());
    }
    assert(c2.find(3)->second == "three");
    assert(c2.find(4)->second == "four");
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator().get_id() == 2);
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef test_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a1[] = {
        P(1, "one"),
        P(2, "two"),
        P(3, "three"),
        P(4, "four"),
        P(1, "four"),
        P(2, "four"),
    };
    P a2[] = {
        P(10, "ten"),
        P(20, "twenty"),
        P(30, "thirty"),
        P(40, "forty"),
        P(50, "fifty"),
        P(60, "sixty"),
        P(70, "seventy"),
        P(80, "eighty"),
    };
    C c1(std::begin(a1), std::end(a1), 0, Hash(1), Compare(1), Alloc(1, 1));
    C c2(std::begin(a2), std::end(a2), 0, Hash(2), Compare(2), Alloc(1, 2));
    c2.max_load_factor(2);
    c1.swap(c2);

    assert(c1.bucket_count() >= 8);
    assert(c1.size() == 8);
    assert(c1.find(10)->second == "ten");
    assert(c1.find(20)->second == "twenty");
    assert(c1.find(30)->second == "thirty");
    assert(c1.find(40)->second == "forty");
    assert(c1.find(50)->second == "fifty");
    assert(c1.find(60)->second == "sixty");
    assert(c1.find(70)->second == "seventy");
    assert(c1.find(80)->second == "eighty");
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator().get_id() == 1);
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    assert(c2.bucket_count() >= 6);
    assert(c2.size() == 6);
    {
      std::set<std::string> s;
      s.insert("one");
      s.insert("four");
      assert(s.find(c2.find(1)->second) != s.end());
      s.erase(s.find(c2.find(1)->second));
      assert(s.find(std::next(c2.find(1))->second) != s.end());
    }
    {
      std::set<std::string> s;
      s.insert("two");
      s.insert("four");
      assert(s.find(c2.find(2)->second) != s.end());
      s.erase(s.find(c2.find(2)->second));
      assert(s.find(std::next(c2.find(2))->second) != s.end());
    }
    assert(c2.find(3)->second == "three");
    assert(c2.find(4)->second == "four");
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator().get_id() == 2);
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }

  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef other_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    C c1(0, Hash(1), Compare(1), Alloc(1));
    C c2(0, Hash(2), Compare(2), Alloc(2));
    c2.max_load_factor(2);
    c1.swap(c2);

    LIBCPP_ASSERT(c1.bucket_count() == 0);
    assert(c1.size() == 0);
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc(2));
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    LIBCPP_ASSERT(c2.bucket_count() == 0);
    assert(c2.size() == 0);
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc(1));
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef other_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a2[] = {
        P(10, "ten"),
        P(20, "twenty"),
        P(30, "thirty"),
        P(40, "forty"),
        P(50, "fifty"),
        P(60, "sixty"),
        P(70, "seventy"),
        P(80, "eighty"),
    };
    C c1(0, Hash(1), Compare(1), Alloc(1));
    C c2(std::begin(a2), std::end(a2), 0, Hash(2), Compare(2), Alloc(2));
    c2.max_load_factor(2);
    c1.swap(c2);

    assert(c1.bucket_count() >= 8);
    assert(c1.size() == 8);
    assert(c1.find(10)->second == "ten");
    assert(c1.find(20)->second == "twenty");
    assert(c1.find(30)->second == "thirty");
    assert(c1.find(40)->second == "forty");
    assert(c1.find(50)->second == "fifty");
    assert(c1.find(60)->second == "sixty");
    assert(c1.find(70)->second == "seventy");
    assert(c1.find(80)->second == "eighty");
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc(2));
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    LIBCPP_ASSERT(c2.bucket_count() == 0);
    assert(c2.size() == 0);
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc(1));
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef other_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a1[] = {
        P(1, "one"),
        P(2, "two"),
        P(3, "three"),
        P(4, "four"),
        P(1, "four"),
        P(2, "four"),
    };
    C c1(std::begin(a1), std::end(a1), 0, Hash(1), Compare(1), Alloc(1));
    C c2(0, Hash(2), Compare(2), Alloc(2));
    c2.max_load_factor(2);
    c1.swap(c2);

    LIBCPP_ASSERT(c1.bucket_count() == 0);
    assert(c1.size() == 0);
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc(2));
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    assert(c2.bucket_count() >= 6);
    assert(c2.size() == 6);
    {
      std::set<std::string> s;
      s.insert("one");
      s.insert("four");
      assert(s.find(c2.find(1)->second) != s.end());
      s.erase(s.find(c2.find(1)->second));
      assert(s.find(std::next(c2.find(1))->second) != s.end());
    }
    {
      std::set<std::string> s;
      s.insert("two");
      s.insert("four");
      assert(s.find(c2.find(2)->second) != s.end());
      s.erase(s.find(c2.find(2)->second));
      assert(s.find(std::next(c2.find(2))->second) != s.end());
    }
    assert(c2.find(3)->second == "three");
    assert(c2.find(4)->second == "four");
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc(1));
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef other_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a1[] = {
        P(1, "one"),
        P(2, "two"),
        P(3, "three"),
        P(4, "four"),
        P(1, "four"),
        P(2, "four"),
    };
    P a2[] = {
        P(10, "ten"),
        P(20, "twenty"),
        P(30, "thirty"),
        P(40, "forty"),
        P(50, "fifty"),
        P(60, "sixty"),
        P(70, "seventy"),
        P(80, "eighty"),
    };
    C c1(std::begin(a1), std::end(a1), 0, Hash(1), Compare(1), Alloc(1));
    C c2(std::begin(a2), std::end(a2), 0, Hash(2), Compare(2), Alloc(2));
    c2.max_load_factor(2);
    c1.swap(c2);

    assert(c1.bucket_count() >= 8);
    assert(c1.size() == 8);
    assert(c1.find(10)->second == "ten");
    assert(c1.find(20)->second == "twenty");
    assert(c1.find(30)->second == "thirty");
    assert(c1.find(40)->second == "forty");
    assert(c1.find(50)->second == "fifty");
    assert(c1.find(60)->second == "sixty");
    assert(c1.find(70)->second == "seventy");
    assert(c1.find(80)->second == "eighty");
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc(2));
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    assert(c2.bucket_count() >= 6);
    assert(c2.size() == 6);
    {
      std::set<std::string> s;
      s.insert("one");
      s.insert("four");
      assert(s.find(c2.find(1)->second) != s.end());
      s.erase(s.find(c2.find(1)->second));
      assert(s.find(std::next(c2.find(1))->second) != s.end());
    }
    {
      std::set<std::string> s;
      s.insert("two");
      s.insert("four");
      assert(s.find(c2.find(2)->second) != s.end());
      s.erase(s.find(c2.find(2)->second));
      assert(s.find(std::next(c2.find(2))->second) != s.end());
    }
    assert(c2.find(3)->second == "three");
    assert(c2.find(4)->second == "four");
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc(1));
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
#if TEST_STD_VER >= 11
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef min_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    C c1(0, Hash(1), Compare(1), Alloc());
    C c2(0, Hash(2), Compare(2), Alloc());
    c2.max_load_factor(2);
    c1.swap(c2);

    LIBCPP_ASSERT(c1.bucket_count() == 0);
    assert(c1.size() == 0);
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    LIBCPP_ASSERT(c2.bucket_count() == 0);
    assert(c2.size() == 0);
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef min_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a2[] = {
        P(10, "ten"),
        P(20, "twenty"),
        P(30, "thirty"),
        P(40, "forty"),
        P(50, "fifty"),
        P(60, "sixty"),
        P(70, "seventy"),
        P(80, "eighty"),
    };
    C c1(0, Hash(1), Compare(1), Alloc());
    C c2(std::begin(a2), std::end(a2), 0, Hash(2), Compare(2), Alloc());
    c2.max_load_factor(2);
    c1.swap(c2);

    assert(c1.bucket_count() >= 8);
    assert(c1.size() == 8);
    assert(c1.find(10)->second == "ten");
    assert(c1.find(20)->second == "twenty");
    assert(c1.find(30)->second == "thirty");
    assert(c1.find(40)->second == "forty");
    assert(c1.find(50)->second == "fifty");
    assert(c1.find(60)->second == "sixty");
    assert(c1.find(70)->second == "seventy");
    assert(c1.find(80)->second == "eighty");
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    LIBCPP_ASSERT(c2.bucket_count() == 0);
    assert(c2.size() == 0);
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef min_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a1[] = {
        P(1, "one"),
        P(2, "two"),
        P(3, "three"),
        P(4, "four"),
        P(1, "four"),
        P(2, "four"),
    };
    C c1(std::begin(a1), std::end(a1), 0, Hash(1), Compare(1), Alloc());
    C c2(0, Hash(2), Compare(2), Alloc());
    c2.max_load_factor(2);
    c1.swap(c2);

    LIBCPP_ASSERT(c1.bucket_count() == 0);
    assert(c1.size() == 0);
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    assert(c2.bucket_count() >= 6);
    assert(c2.size() == 6);
    {
      std::set<std::string> s;
      s.insert("one");
      s.insert("four");
      assert(s.find(c2.find(1)->second) != s.end());
      s.erase(s.find(c2.find(1)->second));
      assert(s.find(std::next(c2.find(1))->second) != s.end());
    }
    {
      std::set<std::string> s;
      s.insert("two");
      s.insert("four");
      assert(s.find(c2.find(2)->second) != s.end());
      s.erase(s.find(c2.find(2)->second));
      assert(s.find(std::next(c2.find(2))->second) != s.end());
    }
    assert(c2.find(3)->second == "three");
    assert(c2.find(4)->second == "four");
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
  {
    typedef test_hash<int> Hash;
    typedef test_equal_to<int> Compare;
    typedef min_allocator<std::pair<const int, std::string> > Alloc;
    typedef std::unordered_multimap<int, std::string, Hash, Compare, Alloc> C;
    typedef std::pair<int, std::string> P;
    P a1[] = {
        P(1, "one"),
        P(2, "two"),
        P(3, "three"),
        P(4, "four"),
        P(1, "four"),
        P(2, "four"),
    };
    P a2[] = {
        P(10, "ten"),
        P(20, "twenty"),
        P(30, "thirty"),
        P(40, "forty"),
        P(50, "fifty"),
        P(60, "sixty"),
        P(70, "seventy"),
        P(80, "eighty"),
    };
    C c1(std::begin(a1), std::end(a1), 0, Hash(1), Compare(1), Alloc());
    C c2(std::begin(a2), std::end(a2), 0, Hash(2), Compare(2), Alloc());
    c2.max_load_factor(2);
    c1.swap(c2);

    assert(c1.bucket_count() >= 8);
    assert(c1.size() == 8);
    assert(c1.find(10)->second == "ten");
    assert(c1.find(20)->second == "twenty");
    assert(c1.find(30)->second == "thirty");
    assert(c1.find(40)->second == "forty");
    assert(c1.find(50)->second == "fifty");
    assert(c1.find(60)->second == "sixty");
    assert(c1.find(70)->second == "seventy");
    assert(c1.find(80)->second == "eighty");
    assert(c1.hash_function() == Hash(2));
    assert(c1.key_eq() == Compare(2));
    assert(c1.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c1.begin(), c1.end())) == c1.size());
    assert(static_cast<std::size_t>(std::distance(c1.cbegin(), c1.cend())) == c1.size());
    assert(c1.max_load_factor() == 2);

    assert(c2.bucket_count() >= 6);
    assert(c2.size() == 6);
    {
      std::set<std::string> s;
      s.insert("one");
      s.insert("four");
      assert(s.find(c2.find(1)->second) != s.end());
      s.erase(s.find(c2.find(1)->second));
      assert(s.find(std::next(c2.find(1))->second) != s.end());
    }
    {
      std::set<std::string> s;
      s.insert("two");
      s.insert("four");
      assert(s.find(c2.find(2)->second) != s.end());
      s.erase(s.find(c2.find(2)->second));
      assert(s.find(std::next(c2.find(2))->second) != s.end());
    }
    assert(c2.find(3)->second == "three");
    assert(c2.find(4)->second == "four");
    assert(c2.hash_function() == Hash(1));
    assert(c2.key_eq() == Compare(1));
    assert(c2.get_allocator() == Alloc());
    assert(static_cast<std::size_t>(std::distance(c2.begin(), c2.end())) == c2.size());
    assert(static_cast<std::size_t>(std::distance(c2.cbegin(), c2.cend())) == c2.size());
    assert(c2.max_load_factor() == 1);
  }
#endif

  return 0;
}
